Silane-Sulfide Chain End Modified Elastomeric Polymers

ABSTRACT

A chain end modified polymer comprising the reaction product of a living anionic elastomeric polymer and a silane-sulfide modifier A preferred class of modifiers includes compounds represented by the formula: (RO) x (R) y Si—R′—S—SiR 3 , wherein Si is silicon; S is sulfur; O is oxygen; x is an integer selected from 1, 2 and 3; y is an integer selected from 0, 1, and 2; x+y=3; R is the same or different and is: (C 1 -C 16 ) alkyl; and R′ is aryl, alkylaryl, or (C 1 -C 16 ) alkyl. The invention further includes methods for making such chain end modified polymers, their use in preparing vulcanized elastomeric polymer compositions, and articles made from such compositions, including pneumatic tires, tire treads, belts, and the like. The subject compositions exhibit lower Tan δ at 60° C. values, while maintaining good processing characteristics, and a good balance of physical properties, including: abrasion resistance, tensile strength, modulus and elongation at break.

REFERENCE TO PRIOR APPLICATION

This application claims the benefit of Provisional Application No.60/728,174 filed on Oct. 19, 2005, incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention generally relates to functionalized or “chain endmodified” elastomeric polymers, their use in the preparation ofelastomeric compositions and articles made therefrom. The inventionspecifically relates to the use of so called “sulfanylsilanes” as chainend modifiers for “living” anionic elastomeric polymers. The polymer“end caps” are reactive with unsaturated portions of the elastomericpolymer backbone and/or with fillers or other components present in anelastomeric composition. These modified elastomeric polymers are usefulin the preparation of vulcanized elastomeric compositions havingrelatively low hysteresis loss. Such compositions are useful in manyarticles including tire treads having low rolling resistance, along witha good balance of other desirable physical and chemical properties, forexample, wet skid properties, abrasion resistance, tensile strength andprocessability.

A major source of hysteresis in vulcanized elastomeric polymers isbelieved to be attributed to free polymer chain ends, that is, thesection of the elastomeric polymer chain between the last cross-link andthe end of the polymer chain. This free end of the polymer does notparticipate in any efficient elastically recoverable process, and as aresult, any energy transmitted to this section of the polymer is lost.This dissipated energy leads to a pronounced hysteresis under dynamicdeformation. The hysteresis loss of an elastomeric polymer compositionis related to its tan δ at 60° C. value. In general, vulcanizedelastomeric polymer compositions having relatively small tan δ at 60° C.values are preferred as having lower hysteresis loss. In tires, thistranslates to a lower rolling resistance and better fuel economy.

One generally accepted approach to reducing hysteresis loss is to reducethe number of free chain ends of elastomeric polymers. Varioustechniques are described in the open literature including the use of“coupling agents,” such as tin tetrachloride, which may functionalizethe polymer chain end and react with unsaturated portions of the polymerbackbone and/or other constituents in an elastomeric composition, suchas a filler. Examples of such techniques along with other documents ofinterest include: U.S. Pat. Nos. 3,281,383; 3,244,664 and 3,692,874(e.g. tetrachlorosilane); U.S. Pat. No. 3,978,103; U.S. Pat. Nos.4,048,206; 4,474,908; U.S. Pat. No. 6,777,569 (blocked mercaptosilanes)and U.S. Pat. No. 3,078,254 (a multi-halogen-substituted hydrocarbonsuch as 1,3,5-tri(bromo methyl)benzene); U.S. Pat. No. 4,616,069 (tincompound and organic amino or amine compound); and U.S. 2005/0124740.

“Synthesis of end-functionalized polymer by means of living anionicpolymerization,” Journal of Macromolecular Chemistry and Physics, 197,(1996), 3135-3148, describes the synthesis of polystyrene andpolyisoprene containing living polymers with hydroxy (—OH) and mercapto(—SH) functional end caps obtained by reacting the living polymer withhaloalkanes containing silyl ether and silyl thioether functions. Thetertiary-butyldimethylsilyl (TBDMS) group is preferred as protectinggroup for the —OH and —SH functions in the termination reactions becausethe corresponding silyl ethers and thioethers are found to be both,stable and compatible with anionic living polymers.

U.S. Pat. No. 6,579,949 describes the use of similar class of sulfurcompounds, including tert-butyl dimethylsilyl-3-chloro-1-propylsulfide(Cl—(CH₂)3-S—Si—(CH₃)₂C(CH₃)₃) to produce rubber articles having lowhysteresis loss. More specifically, the subject sulfur compounds arereacted with anionically-initiated, living polymers to produce chain endmodified polymers, which are subsequently blended with fillers,vulcanizing agents, accelerators, oil extenders, and other variousadditives to produce tires having low hysteresis loss. The tert-butyldimethylsilylpropylsulfide end cap is not easily removed during standardpolymerization conditions, but the protective tert-dimethylsilyl groupis cleaved by reaction with additives containing H⁺, F⁻ or zinccompounds prior to, or during, vulcanization, thus leaving a mercapto(“thiol”) group to react (at least 20 percent) with unsaturated segmentsof the backbone of other elastomeric polymers. Unfortunately, the chainend modification reaction produces lithium chloride. Chloride ionspresent in the reaction strongly accelerate corrosion in processingequipment.

U.S. Pat. No. 6,229,036 discloses a broad class of sulfanylsilanesprepared by reacting mercaptosilanes with chlorosilanes, and their useas coupling agents in rubber mixtures to produce tire treads having lowrolling resistance and good wet grip. Many sulfanylsilane compounds aredescribed including: (EtO)₃—Si—(CH₂)₃—S—Si—(CH₃)₃ and(MeO)₃—Si—(CH₂)₃—S—Si—(C₂H₅)₃. According to this reference, elastomericpolymers are prepared and terminated via conventional techniques, andsubsequently mixed with oxidic fillers and from 0.1 to 15 weight percent(with respect to the filler) of a sulfanylsilane coupling agent, andthen vulcanized to form a rubber product. Thus, unlike the approachdescribed in U.S. Pat. No. 6,579,949, the sulfanylsilane coupling agentis not used as a chain end modifier to a living polymer, but is onlycombined with a post-terminated elastomeric polymer during compounding.This approach is disadvantaged due to the difficulty of distributing thecoupling agent throughout the rubber mixture during compounding. Thatis, unlike the typical low viscous, solvent-based environment associatedwith most anionic polymerizations, the rubber compounding environment istypically highly viscous and solvent free, thus leading to a lesshomogenous distribution of the coupling agent throughout thecomposition. As consequence, the interaction of the functionalizedpolymer with the filler material and/or unsaturated segments of thepolymer backbone is less complete. If the modifier compound is added toa polymer comprising exclusively terminated polymer chains, it is notpossible to efficiently combine (or react) the chain ends of thispolymer with other polymer chains, or with fillers, by using themodifier compound. In addition, it is not possible to efficientlycombine or link the polymer to fillers or other polymer chains.

SUMMARY OF THE INVENTION

The invention provides a chain end modified elastomeric polymer,comprising the reaction product of:

i) a living anionic elastomeric polymer, and

ii) a silane-sulfide modifier represented by the formula:

(RO)_(x)(R)_(y)Si—R′—S—SiR₃,

wherein:

Si is silicon; S is sulfur; O is oxygen;

x is an integer selected from 1, 2 and 3;

y is an integer selected from 0, 1, and 2; x+y=3;

R is the same or different and is (C₁-C₁₆) alkyl; and R′ is aryl,alkylaryl, or (C₁-C₁₆) alkyl.

In another aspect, the invention also provides a vulcanized elastomericpolymer composition, comprising the reaction product of the following:

1) a filler;

2) a vulcanization agent; and

3) a chain end modified elastomeric polymer, and wherein the chain endmodified elastomeric polymer is the reaction product of:

-   -   i) a living anionic elastomeric polymer, and    -   ii) a silane-sulfide modifier represented by the formula:

(RO)_(x)(R)_(y)Si—R′—S—SiR₃

-   -   -   wherein:        -   Si is silicon; S is sulfur; O is oxygen;        -   x is an integer selected from 1, 2 and 3;        -   y is an integer selected from 0, 1, and 2; x+y=3;        -   R is the same or different and is (C₁-C₁₆) alkyl; and        -   R′ is aryl, alkylaryl, or (C₁-C₁₆) alkyl.

In yet another aspect, the invention provides a method for making avulcanized elastomeric polymer composition, comprising combining thefollowing constituents:

1) a filler;

2) a vulcanization agent; and

3) a chain end modified elastomeric polymer, which is the reactionproduct of:

-   -   i) a living anionic elastomeric polymer, and    -   ii) a silane-sulfide modifier represented by the formula:

(RO)_(x)(R)_(y)Si—R′—S—SiR₃

-   -   -   wherein:        -   Si is silicon; S is sulfur; O is oxygen;        -   x is an integer selected from 1, 2 and 3;        -   y is an integer selected from 0, 1, and 2; x+y=3;        -   R is the same or different and is (C₁-C₁₆) alkyl; and        -   R′ is aryl, alkylaryl, or (C₁-C₁₆) alkyl.

The invention also provides a chain end modified elastomeric polymer,comprising the reaction product of:

i) a living anionic elastomeric polymer, and

ii) a silane-sulfide modifier represented by the formula:

GJMSi-A-S—SiTXZ

wherein:

Si is silicon; S is sulfur; G is (C₁-C₁₆) alkoxy;

J and M are the same or different, and are each independently selectedfrom the group consisting of: hydrogen (H), (C₁-C₁₆) alkyl, (C₁-C₁₆)alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆) alkylaryl, and -A-S—SiTXZ (where A, T, Xand Z are defined below);

A is an aryl, an alkylaryl, a (C₇-C₁₆) alkylaryl, or a (C₁-C₁₆) alkylwhich may be linear or branched, saturated or unsaturated and may besubstituted with: (C₁-C₄) alkyl, (C₁-C₄) alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆)aralkyl, nitrile, amine, NO₂, thioalkyl, -A-S—SiTXZ (where A, T, X and Zare defined below); and

T, X and Z groups are the same or different, and are each independentlyselected from the group consisting of: hydrogen (H), (C₁-C₁₆) alkyl,(C₁-C₁₆) alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆) aralkyl, and —S-A-SiMJG (A, M,J and G are defined herein). The invention also provides for avulcanized elastomeric polymer composition comprising this chain endmodified elastomeric polymer, and for methods for preparing the same.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention includes a chain end modified polymer comprisingthe reaction product of a living anionic elastomeric polymer and asilane-sulfide modifier represented by Formula 1, and more preferably byFormula 2, each as presented below. The invention further includesmethods for making such chain end modified polymers, their use inpreparing vulcanized elastomeric polymer compositions, and articles madefrom such compositions such as pneumatic tires, tire treads, belts,footwear and the like.

The subject compositions exhibit lower tan 6 at 60° C. values, whilemaintaining good processing characteristics, and a good balance ofphysical properties, including one or more of the following properties:abrasion resistance, tensile strength, modulus and elongation at break.The subject compositions are useful in preparing tire treads havinglower rolling resistance, while maintaining good wet grip properties.The subject compositions are particularly useful in preparing tiresincluding fillers, such as carbon black, silica, carbon-silica dualphase filler, and the like.

The term “elastomeric polymers” is intended to mean elastomers orrubbers, including cross-linkable polymers, that when cross-linked, haveproperties similar to vulcanized natural rubber (cis-1,4-polyisoprene),for example, stretch under tension and retract relatively quickly toapproximately the original length when released.

The use of lithium initiators to polymerize conjugated diene, triene,and monovinyl aliphatic and aromatic monomers is well known. Thesepolymerizations proceed according to anionic polymerization mechanisms,wherein the reaction of monomers, by nucleophilic initiation, form andpropagate a polymeric structure. Throughout the polymerization, thepolymer structure is ionic or “living.” Thus, the polymer structure hasat least one reactive or “living” end. This is the context of the term“living,” as used herein, to describe the subject elastomeric polymers.

Thus, as discussed above, the term “living anionic elastomeric polymer,”as used herein, refers to a polymer comprising polymer chains, in whicheach chain contains a reactive anionic end group located at “at leastone end” of the polymer chain. This term is known in the art.

As discussed herein, the terms “chain end modified elastomeric polymer,”“chain end modified polymer,” “chain end modified elastomer,” andsimilar terms, as used herein, refer the reaction product of a “livinganionic elastomeric polymer” with a silane-sulfide modifier, as shown inFormula 1 or Formula 2 below. One, or more than one, polymer chain mayreact with one silane-sulfide modifier (see also Formula 5).

In one embodiment, the living anionic elastomeric polymer is selectedfrom the group consisting of homopolymers of isoprene, homopolymers ofbutadiene, copolymers of butadiene with styrene, copolymers of isoprenewith styrene, terpolymers butadiene with isoprene and styrene, andcombinations thereof. In another embodiment, the living anionicelastomeric polymer is selected from the group consisting ofhomopolymers of butadiene and copolymers of butadiene with styrene.

Monomers useful in preparing the subject elastomeric polymers includeconjugated olefins and olefins chosen from the group comprisingα-olefins, internal olefins, cyclic olefins, polar olefins andnonconjugated diolefins. Suitable conjugated unsaturated monomers arepreferably conjugated dienes, such as: 1,3-butadiene,2-alkyl-1,3-butadiene, preferably, isoprene (2-methyl-1,3-butadiene),2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene,1,3-hexadiene, 1,3-heptadiene, 1,3-octadiene, 2-methyl-2,4-pentadiene,cyclopentadiene, 2,4-hexadiene, 1,3-cyclooctadiene. Preferred olefinsare C₂₋₂₀ α-olefins including, but not limited to, long chainmacromolecular α-olefins, more especially an aromatic vinyl compound.Preferred aromatic vinyl compounds are styrene, including C₁₋₄ alkylsubstituted styrene, such as 2-methylstyrene, 3-methylstyrene,4-methylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene,α-methylstyrene and stilbene, 2,4-diisopropylstyrene,4-tert-butylstyrene, vinyl benzyl dimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethyl styrene, tert-butoxystyrene,vinylpyridine, and mixtures thereof. Suitable polar olefins includedacrynitrile, methacrylates, methylmethacrylate. Suitable nonconjugatedolefins include: C₄₋₂₀ diolefins, especially norbornadiene,ethylidenenorbornene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene,4-vinylcyclohexene, divinylbenzene including 1,2-divinylbenzene,1,3-divinylbenzene and 1,4-divinylbenzene and mixtures thereof.Preferred conjugated dienes include: butadiene, isoprene andcyclopentadiene, and preferred aromatic α-olefins include: styrene and4-methylstyrene.

Examples of applicable elastomeric polymers include homopolymers ofconjugated dienes, especially butadiene or isoprene, and random or blockco- and terpolymers of at least one conjugated diene, especiallybutadiene or isoprene, with at least one aromatic α-olefin, especiallystyrene and 4-methylstyrene, aromatic diolefin, especiallydivinylbenzene. Especially preferred is the random copolymerization,optionally terpolymerization, of at least one conjugated diene with atleast one aromatic α-olefin, and optionally, at least one aromaticdiolefin or aliphatic α-olefin, especially butadiene or isoprene withstyrene, 4-methylstyrene and/or divinylbenzene.

Preferred modified elastomeric polymers (or modified polymers) includemodified polybutadiene, modified polyisoprene, modifiedstyrene-butadiene copolymer, modified styrene-isoprene copolymer,modified butadiene-isoprene copolymer, and modified isoprene-styrenecopolymer. More preferred elastomers (or polymers) include modifiedpolybutadiene and modified styrene-butadiene copolymer. The terms“modified elastomeric polymers” and “modified polymers” refer to the“chain end modified polymers” as discussed above.

In one embodiment, the modified elastomeric polymer is selected from thegroup consisting of modified homopolymers of isoprene, modifiedhomopolymers of butadiene, modified copolymers of butadiene withstyrene, modified copolymers of isoprene with styrene, modifiedterpolymers butadiene with isoprene and styrene, and combinationsthereof. In another embodiment, the modified elastomeric polymer isselected from the group consisting of modified homopolymers of butadieneand modified copolymers of butadiene with styrene.

In general, the polymerization of the diene monomer(s) orcopolymerization of the diene monomer(s) with the α-olefin monomer(s)may be accomplished at conditions well known in the art for anionicliving type polymerization reactions, such as temperatures from −50 to250° C., preferably from 0 to 120° C. The reaction temperature may bethe same as the polymerization initiation temperature. Thepolymerization can be effected at atmospheric pressure, atsub-atmospheric pressure, or at elevated pressures of up to, or evenhigher than, 500 MPa, continuously or discontinuously. Preferably, thepolymerization is performed at pressures from 0.01 to 500 MPa, mostpreferably from 0.01 to 10 MPa, and in particular from 0.1 to 2 MPa.Higher pressures can be applied. In such a high-pressure process theinitiator according to the present invention can also be used with goodresults. Solution polymerizations normally take place at lowerpressures, preferably below 10 MPa. The polymerization can be carriedout in the gas phase as well as in a liquid reaction medium. Thepolymerization is generally conducted under batch, continuous orsemi-continuous polymerization conditions. The polymerization processcan be conducted as a gas phase polymerization (for example, in afluidized bed or stirred bed reactor), as a solution polymerization,wherein the polymer formed is substantially soluble in the reactionmixture, a suspension/slurry polymerization, wherein the polymer formedis substantially insoluble in the reaction medium or as a so-called bulkpolymerization process, in which an excess of monomer to be polymerizedis used as the reaction medium.

Polymerization of the aforementioned monomers is typically initiatedwith an anionic initiator, such as, but not limited to, an organo metalcompound having at least one lithium, sodium, potassium or magnesiumatom, the organo metal compounds containing from 1 to about 20 carbonatoms. Preferably the organo metal compound has at least one lithiumatom, such as: ethyl lithium, propyl lithium, n-butyl lithium, sec-butyllithium, tert-butyl lithium, phenyl lithium, hexyl lithium,1,4-dilithio-n-butane, 1,3-di(2-lithio-2-hexyl)benzene, preferablyn-butyl lithium and sec-butyl lithium. These organo lithium initiatorsmay be used alone or in combination as a mixture of two or moredifferent kinds. The amount of organo lithium initiator used variesbased upon the monomers being polymerized and on the target molecularweight of the produced polymer; however, the amount is typically 0.1 to5 mmol, preferably 0.3 to 3 mmol per 100 grams of monomer (totalpolymerizable monomer).

Polar coordinator compounds may be optionally added to thepolymerization mixture to adjust the microstructure (the content ofvinyl bond) of the conjugated diolefin portion of the “diolefin-typehomo-, copolymer or terpolymer,” or to adjust the compositiondistribution of the aromatic vinyl compound in the “conjugated dienemonomer containing co- or terpolymer,” and thus, for example, to serveas randomizer component. Polar coordinator compounds are, for example,but not limited to, ether compounds, such as diethyl ether, di-n-butylether, ethylene glycol diethyl ether, ethylene glycol dibutylether,diethylene glycol dimethyl ether, propylene glycol dimethyl ether,propylene glycol diethyl ether, propylene glycol dibutylether,alkyltetrahydroforylethers, such as, methyltetrahydrofurylether,ethyltetrahydrofurylether, propyltetrahydrofurylether,butyltetrahydrofurylether, hexyltetrahydrofarylether,octyltetrahydrofurylether, tetrahydrofuran,2,2-(bistetrahydrofurfuryl)propane. bistetrahydrofurfurylformal, methylether of tetrahydrofurfuryl alcohol, ethyl ether of tetrahydrofarfurylalcohol, butyl ether of tetrahydrofurfuryl alcohol,α-methoxytetrahydrofuran, dimethoxybenzene, and dimethoxyethane and/ortertiary amine compounds such as butyl ether of triethylamine, pyridine,N,N,N′,N′-tetramethyl ethylenediamine, dipiperidinoethane, methyl etherof N,N-diethylethanolamine, ethyl ether of N,N-diethylethanolamine, andN,N-diethylethanolamine. The polar coordinator compound will typicallybe added at a molar ratio of the polar coordinator compound to thelithium initiator within the range of about 0.012:1 to about 5:1, buttypically about 0.1:1 to about 4:1, preferably 0.25:1 to about 3:1, andmore preferably 0.5:1 to about 3:2.

The polymerization can optionally be conducted utilizing an oligomericoxolanyl alkane as a polar coordinator compound. Examples of suchcompounds are provided in U.S. Pat. Nos. 6,790,921 and 6,664,328, eachincorporated herein by reference.

The polymerization can optionally include accelerators to increase thereactivity of the initiator, to randomly arrange aromatic vinylcompounds introduced in the polymer, or to provide a single chain ofaromatic vinyl compounds, and thus influencing the compositiondistribution of the aromatic vinyl compounds in a “conjugated dienecontaining modified copolymer or terpolymer” of the invention. Examplesof applicable accelerators include sodium and potassium alkoxides orpotassium phenoxides, such as potassium isopropoxide, potassiumt-butoxide, potassium t-amyloxide, potassium n-heptaoxide, potassiumbenzyloxide, potassium phenoxide; potassium salts of carboxylic acidssuch as isovalerianic acid, caprylic acid, lauryl acid, palmitic acid,stearic acid, oleic acid, linolenic acid, benzoic acid, phthalic acid,or 2-ethylhexanoic acid; potassium salts of organic sulfonic acids suchas dodecyl benzenesulfonic acid, tetradecyl benzenesulfonic acid,hexadecyl benzenesulfonic acid, or octadecyl benzenesulfonic acid; andpotassium salts of organic phosphorous acids such as diethyl phosphite,diisopropyl phosphite, diphenyl phosphite, dibutyl phosphite, anddilauryl phosphite. These potassium compounds may be added in an amountof 0.005-0.5 mol for 1.0 gram atom equivalent of lithium initiator. Ifless than 0.005 mol are added, a sufficient effect is not typicallyachieved. On the other hand, if the amount of the potassium compound ismore than about 0.5 mol, the productivity and efficiency of chain endmodification reaction is significantly reduced.

An alkali metal alkoxide compound may also be added together with thepolymerization initiator to increase the polymerization reactivity. Thealkali metal alkoxide compound can be prepared by reacting an alcoholand an organic alkali metal compound. This reaction may be carried outin a hydrocarbon solvent in the presence of monomers, preferablyconjugated diolefin monomers and aromatic vinyl compound monomers priorto the copolymerization of these monomers. Alkali metal alkoxidecompound are exemplary represented by metal alkoxides oftetrahydrofurfuryl alcohol, N,N-dimethyl ethanolamine, N,N-diethylethanolamine, 1-piperazine ethanolamine, or the like. An organic alkalimetal compound preferably may be an organolithium compound, and can beused as reactant for an alcohol compound to prepare an alkali metalalkoxide. For example, ethyl lithium, propyl lithium, n-butyllithium,sec-butyl lithium, tert-butyl lithium, and hexyl lithium, and mixturesof these can be given. Of these, n-butyl lithium and sec-butyl lithiumare preferable. The molar ratio of an alcoholic compound and anorganolithium compound should be from 1:0.7 to 1:5.0, preferably from1:0.8 to 1:2.0, and more preferably from 1:0.9 to 1:1.2. If the molarratio of an organolithium compound to an alcoholic compound is more than5.0, the effect on improvement of tensile strength, abrasion resistance,and hysteresis is compromised. On the other hand, a molar ratio of theorganolithium compound smaller than 0.8 retards the speed ofpolymerization and significantly decreases productivity giving rise tolow efficiency of the chain end modification reaction.

To further control polymer molecular weight and polymer properties, acoupling agent or linking agent may be employed. For example, a tinhalide, a silicon halide, a tin alkoxide, a silicon alkoxide, or amixture of the aforementioned compounds, can be continuously addedduring the polymerization, in cases where asymmetrical coupling isdesired. This continuous addition is normally done in a reaction zoneseparate from the zone where the bulk of the polymerization isoccurring. The coupling agent can be added in a hydrocarbon solution,for example, cyclohexane, to the polymerization admixture with suitablemixing for distribution and reaction. The coupling agent will typicallybe added only after a high degree of conversion has already beenattained. For instance, the coupling agent will normally be added onlyafter a monomer conversion of greater than about 85 percent has beenrealized. It will typically be preferred for the monomer conversion toreach at least about 90 percent before the coupling agent is added.Common halide coupling agents include tin tetrachloride, tintetrabromide, tin tetrafluoride, tin tetraiodide, silicon tetrachloride,silicon tetrabromide, silicon tetrafluoride, silicon tetraiodide, tinand silicon trihalides or tin and silicon dihalides can also be used.Polymers coupled with tin or silicon tetrahalides have a maximum of fourarms (or four coupled polymer chains), tin and silicon trihalides have amaximum of three arms and tin and silicon dihalides have a maximum oftwo arms. Hexahalo disilanes or hexahalo disiloxanes can also be used ascoupling agents resulting in polymers with a maximum of six arms. Usefultin and silicon halides coupling agents include: SnCl₄, (R₁)₃SnCl,(R₁)₂SnCl₂, R₁SnCl₃, SiCl₄, (R₁)₃SiCl, (R₁)₂SiCl₂, R₁SiCl₃, Cl₃Si—SiCl₃,Cl₃Si—O—SiCl₃, Cl₃Sn—SnCl₃, Cl₃Sn—O—SnCl₃. Examples of tin and siliconalkoxides coupling agents include: Sn(OMe)₄, Si(OMe)₄, Sn(OEt)₄ orSi(OEt)₄. The most preferred coupling agents are: SnCl₄, SiCl₄, Sn(OMe)₄and Si(OMe)₄.

In one embodiment, the chain end modified elastomeric polymer furthercomprises at least one coupling agent, selected from the groupconsisting of tin halide, tin alkoxide, silicon halide, and siliconalkoxide.

A combination of a tin or silicon compound, as described before, canoptionally be used to couple the polymer. By using such a combination oftin and silicon coupling agents, improved properties for tire rubbers,such as lower hysteresis, can be attained. It is particularly desirableto utilize a combination of tin and silicon coupling agents in tiretread compounds that contain both silica and carbon black. In suchcases, the molar ratio of the tin to the silicon compound employed incoupling the elastomeric polymer will normally be within the range of20:80 to 95:5; more typically 40:60 to 90:10, and preferably 60:40 to85:15. Most typically, a range of about 0.01 to 4.5 milliequivalents ofcoupling agent (tin and silicon compound) is employed per 100 grams ofthe elastomeric polymer. It is normally preferred to utilize about 0.01to about 1.5 milliequivalents of the coupling agent per 100 grams ofpolymer to obtain the desired Mooney viscosity. The larger quantitiestend to produce polymers containing terminally reactive groups orinsufficient coupling. Between zero and less than one equivalent of tinand/or silicon coupling group per equivalent of lithium initiator isused to enable subsequent functionalization of the remaining livingpolymer fraction. For instance, if a tin or silicon tetrachloride, or amixture of these compounds, is used as the coupling agent, between 0 andless than 1.0 mol, preferably between 0 and 0.8 mol, and more preferablybetween 0 and 0.6 mol, of the coupling agent is utilized for every 4.0moles of live lithium polymer chain ends. The coupling agent can beadded in a hydrocarbon solution, e.g. in cyclohexane, to thepolymerization admixture in the reactor with suitable mixing fordistribution and reaction.

For solution based polymerization processes, the polymerization isconducted in a suitable solvent, dispersion agents or diluent.Non-coordinating, inert liquids are preferred, including, but notlimited to, straight and branched-chain hydrocarbons, such as propane,butane, isobutane, pentane, hexane, heptane, octane, cyclic andalicyclic hydrocarbons, such as cyclohexane, cycloheptane,methylcyclohexane, methylcycloheptane, aromatic and alkyl-substitutedaromatic compounds, such as benzene, toluene, and xylene, and isomers ofthe foregoing, and mixtures thereof, as well as pentamethyl heptane ormineral oil fractions, such as light or regular petrol, naphtha,kerosene or gas oil. Fluorinated hydrocarbon fluids, such asperfluorinated C₄₋₁₀ alkanes are also suitable. Further, suitablesolvents, including liquid olefins, which may act as monomers orcomonomers in the polymerization process, including propylene, 1-butene,1-pentene, cyclopentene, 1-hexene, 3-methyl-1-pentene,4-methyl-1-pentene, butadiene, isoprene, 1,4-hexadiene, 1,7-octadiene,1-octene, 1-decene, styrene, divinylbenzene, ethylidenenorbornene,allylbenzene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene,4-vinylcyclohexene, and vinylcyclohexane. Mixtures of the solvents arealso suitable. Aromatic hydrocarbons, for instance benzene and toluene,can also be used.

The terms “chain end modifier”, “end cap modifier”, “modifying agent”,“modifying compound”, and simply “modifier” are all intended to mean thesubject silane-sulfide compounds described herein, with reference toFormulae 1 and 2 below. The terms “chain end modified elastomericpolymer” and “modified elastomeric polymer” are both intended to meanthe reaction product of a living elastomeric polymer with a subjectchain end modifier.

The subject modifier includes compounds according to Formula 1:

GJMSi-A-S—SiTXZ  (Formula 1),

wherein:

Si is silicon; S is sulfur; G is (C₁-C₁₆) alkoxy, preferably a (C₁-C₁₀)alkoxy, more preferably a (C₁-C₆) alkoxy, and even more preferably a(C₁-C₄) alkoxy; and

J and M are the same or different, and are each independently selectedfrom the group consisting of: hydrogen (H), (C₁-C₁₆) alkyl, (C₁-C₁₆)alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆) alkylaryl, and -A-S—SiTXZ (where A, T, Xand Z are defined below); but are preferably independently selected from(C₁-C₅) alkyl and (C₁-C₅) alkoxy.

A is an aryl, an alkylaryl, a (C₇-C₁₆) alkylaryl, or a (C₁-C₁₆) alkylwhich may be linear or branched, saturated or unsaturated and may besubstituted with: (C₁-C₄) alkyl, (C₁-C₄) alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆)aralkyl, nitrile, amine, NO₂, thioalkyl, -A-S—SiTXZ (where A, T, X and Zare defined herein), but is preferably a linear or branched (C₁-C₅)alkyl.

In a preferred embodiment, A is a (C₁-C₁₆) alkyl, more preferably a(C₁-C₁₂) alkyl, even more preferably a (C₁-C₈) alkyl, and mostpreferably a (C₁-C₅) alkyl. In another embodiment, A is a (C₇-C₁₆)alkylaryl, more preferably a (C₇-C₁₂) alkylaryl, most preferably a(C₇-C₁₀) alkylaryl. The designations, (C₁-C_(n)) or (C₇-C_(n)), where nis the upper carbon limit, as used herein, refers to the total number ofcarbon atoms within the “A” group.

In another embodiment, A is preferably a (C₁-C₁₆) alkyl that does notcontain a heteroatom, such as O, N, P or S, and more preferably a(C₁-C₁₂) alkyl that does not contain a heteroatom, such as O, N, P or S,even more preferably a (C₁-C₈) alkyl that does not contain a heteroatom,such as O, N, P or S, and most preferably a (C₁-C₅) alkyl that does notcontain a heteroatom, such as O, N, P or S. In another embodiment, A isa (C₇-C₁₆) alkylaryl that does not contain a heteroatom, such as O, N, Por S, more preferably a (C₇-C₁₂) alkylaryl that does not contain aheteroatom, such as O, N, P or S, and most preferably a (C₇-C₁₀)alkylaryl that does not contain a heteroatom, such as O, N, P or S. Asdiscussed above, the designations, (C₁-C_(n)) or (C₇-C_(n)), where n isthe upper carbon limit, as used herein, refers to the total number ofcarbon atoms within the “A” group.

In a preferred embodiment, the A group, when an alkyl, contains three tofive carbon atoms.

Examples of (C₇-C₈) alkylaryl based A groups include the followingstructures:

The T, X and Z groups are the same or different, and are eachindependently selected from the group consisting of: hydrogen (H),(C₁-C₁₆) alkyl, (C₁-C₁₆) alkoxy, (C₇-C₁₆) aryl, (C₇-C₁₆) aralkyl, and—S-A-SiMJG (A, M, J and G are defined as described herein), butpreferably T, X and Z are independently selected from (C₁-C₅) alkyl and(C₁-C₅) alkoxy, and more preferably T, X and Z are each a (C₁-C₅) alkylgroup. In another embodiment, T, X and Z are each independently a(C₁-C₁₆) alkyl, more preferably a (C₁-C₁₂) alkyl, even more preferably a(C₁-C₈) alkyl, and most preferably a (C₁-C₈) alkyl.

While not shown in Formula 1, it will be understood that the subjectcompounds may also include their corresponding Lewis base adducts (forexample, with solvent molecules tetrahydrofurane, diethylether,dimethoxyethane coordinated with silicon atoms).

In a preferred embodiment of the invention, the modifier as depicted inFormula 1 (see above) and Formula 2 (see below) does not contain ahalide moiety, and more preferably does not contain chloride, which canpotentially form corrosive by-products.

The term “alkyl” is understood to include both straight chainhydrocarbons, (for example, methyl (Me), ethyl (Et), n-propyl (Pr),n-butyl (Bu), n-pentyl, n-hexyl, etc.), branched hydrocarbon groups(e.g. isopropyl, tert-butyl, etc.) and hydrocarbon based non-aromaticrings. These hydrocarbon groups may be optionally substituted withalkyl, alkoxy, hydroxyl, or other heteroatoms, such as nitrogen, sulfurand phosphorous, but preferably do not contain heteroatom-containingsubstitutions.

The term “alkoxy” is understood to include methoxy (MeO), ethoxy (EtO),propoxy (PrO), butoxy (BuO), isopropoxy, isobutoxy, pentoxy, and thelike.

The term “aryl” is understood to include phenyls, biphenyls and otherbenzenoid compounds, optionally substituted with alkyl, alkoxy,hydroxyl, or other heteroatoms, such as nitrogen, sulfur andphosphorous. The aryl groups as defined in Formula 1, preferably containno heteroatom substitution, and even more preferably contain only onearomatic ring, and most preferably contain a six carbon aromatic ring.

The term “alkylaryl” is understood to mean an aryl group bonded to analkyl group. The designation of (C₇-C₁₆) and similar designations, areintended to mean the total number of carbon atoms within the group. Thealkylaryl groups as defined in Formula 1 preferably contain noheteroatom substitution, and even more preferably contain only onearomatic ling, and most preferably contain a six carbon aromatic ring.

More preferably, the subject modifier is selected from the class definedby Formula 2:

(RO)_(x)(R)_(y)Si—R′—S—SiR₃  (Formula 2),

wherein:

O is oxygen, x is an integer selected from 1, 2 and 3; y is an integerselected from 0, 1, and 2; x+y=3.

R is the same or different and is: (C₁-C₁₆) alkyl, preferably (C₁-C₈)alkyl and more preferably (C₁-C₅) alkyl especially including: Me, Et, Prand Bu; and R′ is (C₁-C₁₆) alkyl, preferably (C₁-C₅) alkyl.

-   -   R′ is equivalent to the “A” group, and is thus defined        accordingly, as discussed above.

In a preferred embodiment, each R group is the same or different, andeach is independently a (C₁-C₅) alkyl, and R′ is (C₁-C₅) alkyl.

While not shown in Formula 2, it will be understood that the subjectcompounds include their corresponding Lewis base adducts (e.g. withsolvent molecules tetrahydrofurane, diethylether, dimethoxyethanecoordinated with silicon atoms). Specific preferred species of thesubject modifier include the compounds (and their corresponding Lewisbase adducts which are not shown) represented by the following formulae:

(MeO)₃Si—(CH₂)₃—S—SiMe₃, (EtO)₃Si—(CH₂)₃—S—SiMe₃,(PrO)₃Si—(CH₂)₃—S—SiMe₃, (BuO)₃Si—(CH₂)₃—S—SiMe₃,(MeO)₃Si—(CH₂)₂—S—SiMe₃, (EtO)₃Si—(CH₂)₂—S—SiMe₃,(PrO)₃Si—(CH₂)₂—S—SiMe₃, (BuO)₃Si—(CH₂)₂—S—SiMe₃, (MeO)₃Si—CH₂—S—SiMe₃,(EtO)₃Si—CH₂—S—SiMe₃, (PrO)₃Si—CH₂—S—SiMe₃, (BuO)₃Si—CH₂—S—SiMe₃,(MeO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₃, (EtO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₃,(PrO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₃, (BuO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₃,((MeO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₃, (EtO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(PrO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₃, (BuO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(MeO)₂(Me)Si—(CH₂)₃—S—SiMe₃, (EtO)₂(Me)Si—(CH₂)₃—S—SiMe₃,(PrO)₂(Me)Si—(CH₂)₃—S—SiMe₃, (BuO)₂(Me)Si—(CH₂)₃—S—SiMe₃,(MeO)₂(Me)Si—(CH₂)₂—S—SiMe₃, (EtO)₂(Me)Si(CH₂)₂—S—SiMe₃,(PrO)₂(Me)Si—(CH₂)₂—S—SiMe₃, (BuO)₂(Me)Si—(CH₂)₂—S—SiMe₃,(MeO)₂(Me)Si—CH₂—S—SiMe₃, (EtO)₂(Me)Si—CH₂—S—SiMe₃,(PrO)₂(Me)Si—CH₂—S—SiMe₃, (BuO)₂(Me)Si—CH₂—S—SiMe₃,(MeO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₃, (EtO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₃,(PrO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₃, (BuO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₃,((MeO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(EtO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(PrO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(BuO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₃, (MeO)(Me)₂Si—(CH₂)₃—S—SiMe₃,(EtO)(Me)₂Si—(CH₂)₃—S—SiMe₃, (PrO) Me)₂Si—(CH₂)₃—S—SiMe₃,(BuO)(Me)₂Si—(CH₂)₃—S—SiMe₃, (MeO)(Me)₂Si—(CH₂)₂—S—SiMe₃,(EtO)(Me)₂Si—(CH₂)₂—S—SiMe₃, (PrO)(Me)₂Si—(CH₂)₂—S—SiMe₃,(BuO)(Me)₂Si—(CH₂)₂—S—SiMe₃, (MeO)(Me)₂Si—CH₂—S—SiMe₃,(EtO)(Me)₂Si—CH₂—S—SiMe₃, (PrO)(Me)₂Si—CH₂—S—SiMe₃,(BuO)(Me)₂Si—CH₂—S—SiMe₃, (MeO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₃,(EtO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₃, (PrO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₃,(BuO) (Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₃,((MeO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(EtO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(PrO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₃,(BuO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₃, (MeO)₃Si—(CH₂)₃—S—SiEt₃,(EtO)₃Si—(CH₂)₃—S—SiEt₃, (PrO)₃Si—(CH₂)₃—S—SiEt₃,(BuO)₃Si—(CH₂)₃—S—SiEt₃, (MeO)₃Si—(CH₂)₂—S—SiEt₃,(EtO)₃Si—(CH₂)₂—S—SiEt₃, (PrO)₃Si—(CH₂)₂—S—SiEt₃,(BuO)₃Si—(CH₂)₂—S—SiEt₃, (MeO)₃Si—CH₂—S—SiEt₃, (EtO)₃Si—CH₂—S—SiEt₃,(PrO)₃Si—CH₂—S—SiEt₃, (BuO)₃Si—CH₂—S—SiEt₃,(MeO)₃Si—CH₂—CMe₂-CH₂—S—SiEt₃, (EtO)₃Si—CH₂—CMe₂-CH₂—S—SiEt₃,(PrO)₃Si—CH₂—CMe₂-CH₂—S—SiEt₃, (BuO)₃Si—CH₂—CMe₂-CH₂—S—SiEt₃,((MeO)₃Si—CH₂—C(H)Me-CH₂—S—SiEt₃, (EtO)₃Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(PrO)₃Si—CH₂—C(H)Me-CH₂—S—SiEt₃, (BuO)₃Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(MeO)₂(Me)Si—(CH₂)₃—S—SiEt₃, (EtO)₂(Me)Si—(CH₂)₃—S—SiEt₃,(PrO)₂(Me)Si—(CH₂)₃—S—SiEt₃, (BuO)₂(Me)Si—(CH₂)₃—S—SiEt₃,(MeO)₂(Me)Si—(CH₂)₂—S—SiEt₃, (EtO)₂(Me)Si—(CH₂)₂—S—SiEt₃,(PrO)₂(Me)Si—(CH₂)₂—S—SiEt₃, (BuO)₂(Me)Si—(CH₂)₂—S—SiEt₃,(MeO)₂(Me)Si—CH₂—S—SiEt₃, (EtO)₂(Me)Si—CH₂—S—SiEt₃,(PrO)₂(Me)Si—CH₂—S—SiEt₃, (BuO)₂(Me)Si—CH₂—S—SiEt₃,(MeO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiEt₃, (EtO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiEt₃,(PrO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiEt₃, (BuO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiEt₃,((MeO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(EtO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(PrO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(BuO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiEt₃, (MeO)(Me)₂Si—(CH₂)₃—S—SiEt₃,(EtO)(Me)₂Si—(CH₂)₃—S—SiEt₃, (PrO)(Me)₂Si—(CH₂)₃—S—SiEt₃,(BuO)(Me)₂Si—(CH₂)₃—S—SiEt₃, (MeO)(Me)₂Si—(CH₂)₂—S—SiEt₃,(EtO)(Me)₂Si—(CH₂)₂—S—SiEt₃, (PrO)(Me)₂Si—(CH₂)₂—S—SiEt₃,(BuO)(Me)₂Si—(CH₂)₂—S—SiEt₃, (MeO)(Me)₂Si—CH₂—S—SiEt₃,(EtO)(Me)₂Si—CH₂—S—SiEt₃, (PrO)(Me)₂Si—CH₂—S—SiEt₃,(BuO)(Me)₂Si—CH₂—S—SiEt₃, (MeO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiEt₃,(EtO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiEt₃, (PrO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiEt₃,(BuO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiEt₃, ((MeO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(EtO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiEt₃,(PrO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiEt₃, and(BuO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiEt₃, (MeO)₃Si—(CH₂)₃—S—SiMe₂ ^(t)Bu,(EtO)₃Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (PrO)₃Si—(CH₂)₃—S—SiMe^(t)Bu,(BuO)₃Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (MeO)₃Si—(CH₂)₂—S—SiMe₂ ^(t)Bu,(EtO)₃Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (PrO)₃Si—(CH₂)₂—S—SiMe₂ ^(t)Bu,(BuO)₃Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (MeO)₃Si—CH₂—S—SiMe₂ ^(t)Bu,(EtO)₃Si—CH₂—S—SiMe₂ ^(t)Bu, (PrO)₃Si—CH₂—S—SiMe₂ ^(t)Bu,(BuO)₃Si—CH₂—S—SiMe₂ ^(t)Bu, (MeO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(EtO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu, (PrO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₂^(t)Bu, (BuO)₃Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,((MeO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu, (EtO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₂^(t)Bu, (PrO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,(BuO)₃Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu, (MeO)₂(Me)Si—(CH₂)₃—S—SiMe₂^(t)Bu, (EtO)₂(Me)Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (PrO)₂(Me)Si—(CH₂)₃—S—SiMe₂^(t)Bu, (BuO)₂(Me)Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (MeO)₂(Me)Si—(CH₂)₂—S—SiMe₂^(t)Bu, (EtO)₂(Me)Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (PrO)₂(Me)Si—(CH₂)₂—S—SiMe₂^(t)Bu, (BuO)₂(Me)Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (MeO)₂(Me)Si—CH₂—S—SiMe₂^(t)Bu, (EtO)₂(Me)Si—CH₂—S—SiMe₂ ^(t)Bu, (PrO)₂(Me)Si—CH₂—S—SiMe₂^(t)Bu, (BuO)₂(Me)Si—CH₂—S—SiMe₂ ^(t)Bu,(MeO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(EtO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(PrO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(BuO)₂(Me)Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,((MeO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu₃,(EtO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,(PrO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,(BuO)₂(Me)Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu, (MeO)(Me)₂Si—(CH₂)₃—S—SiMe₂^(t)Bu, (EtO)(Me)₂Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (PrO) Me)₂Si—(CH₂)₃—S—SiMe₂^(t)Bu, (BuO)(Me)₂Si—(CH₂)₃—S—SiMe₂ ^(t)Bu, (MeO)(Me)₂Si—(CH₂)₂—S—SiMe₂^(t)Bu, (EtO)(Me)₂Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (PrO)(Me)₂Si—(CH₂)₂—S—SiMe₂^(t)Bu, (BuO)(Me)₂Si—(CH₂)₂—S—SiMe₂ ^(t)Bu, (MeO)(Me)₂Si—CH₂—S—SiMe₂^(t)Bu, (EtO)(Me)₂Si—CH₂—S—SiMe₂ ^(t)Bu, (PrO)(Me)₂Si—CH₂—S—SiMe₂^(t)Bu, (BuO)(Me)₂Si—CH₂—S—SiMe₂ ^(t)Bu,(MeO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(EtO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(PrO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,(BuO)(Me)₂Si—CH₂—CMe₂-CH₂—S—SiMe₂ ^(t)Bu,((MeO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,(EtO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,(PrO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu, and(BuO)(Me)₂Si—CH₂—C(H)Me-CH₂—S—SiMe₂ ^(t)Bu,

The modifiers of the present invention may be prepared by reacting asulfur containing compound according to Formula 3:

(RO)_(x)(R)_(y)Si—R′—S—H  (Formula 3),

wherein the symbols have the same meaning as defined with respect toFormula 2, with a compound according to Formula 4:

QSiR₃  (Formula 4),

wherein Q is fluorine, chlorine or bromine atom.

The subject modifier includes the sulfanylsilane compounds described inU.S. Pat. No. 6,229,036 (which, to the fullest extent permitted by law,is incorporated herein by reference, including the methods for preparingsulfanylsilane compounds). Of the sulfanylsilane compounds disclosed,those without halogens are preferred.

The modifier may be added intermittently (or at regular or irregularintervals) or continuously during the polymerization, but is preferablyadded at a conversion rate of the polymerization of more than 80%, andmore preferably at a conversion rate of more than 90%. Preferably, asubstantial amount of the polymer chain ends are not terminated prior tothe reaction with the modifier; that is, the living polymer chain endsare present and capable of reacting with the modifier in a polymer chainend modification reaction. The modification reaction may be before,after or during the addition of a coupling agent (if used). Preferablythe modification reaction is completed after the addition of thecoupling agent (if used). In some embodiments, more than a third of thepolymer chain ends are reacted with a coupling agent(s) prior toaddition of the modifier. In some embodiments, no coupling agent is usedand the living polymer chains are reacted with the modifier. In thecourse of the modification reaction one or more than one polymer chaincan react with the modifier. As result one or more than one polymerchain is linked to the functionality derived from the modifier compound.The modifier may be directly added into the polymer solution withoutdilution; however, it may be beneficial to provide addition of themodifier in solution, such as an inert solvent (e.g. cyclohexane). Theamount of modifier added to the polymerization varies depending upon themonomer species, modifier species, reaction conditions, and desired endproperties, but is generally from 0.05 to 5 mol-equivalent, preferablyfrom 0.1 to 2.0 mol-equivalent and most preferably from 0.2 to 1.5mol-equivalent per mol equivalent of alkali metal in the organic alkalimetal compound required as initiator for the polymerization. Themodification reaction may be carried out in a temperature range of 0° C.to 150° C., preferably between 15° C. and 100° C., and even morepreferably between 25° C. and 80° C. There is no limitation for theduration of the functionalization reaction, however with respect to aneconomical polymerization process, the modification reaction is usuallystopped about 10 to 60 minutes after the addition of the modifier.

The chain end modification reaction is believed to result in a chain endmodified elastomeric polymer represented by Formula 5:

(D)_(z)(RO)_(x)(R)_(y)Si—R′—S—SiR₃  (Formula 5),

wherein D is an elastomeric polymer, x is an integer selected from 0, 1and 2; y is an integer selected from 0, 1, and 2; z is an integerselected from 1, 2 and 3, and x+y+z=3, and all other symbols are asprevious defined with respect to Formula 2. While not shown in Formula5, it will be understood that the subject compound(s) include theircorresponding Lewis base adducts. In some preferred embodiments, thechain end modified polymer may be partially coupled via reaction withthe aforementioned coupling agent(s).

While not wishing to be bound by theory, the trialkylsilyl (—SiR₃) groupof Formula 5 is believed to function as a protective group whichprevents unintended subsequent reaction. This “protective” trialkylsilyl(—SiR₃) may be removed by exposure to a compounds containing —OH groupssuch water, alcohols, anionic acids or organic acids, (e.g. hydrochloricacid, sulfuric acid or carboxylic acids), thus forming an “un-protected”thiol (—SH) group. Such conditions are typically present duringvulcanization. Depending on the polymer “work up” conditions, both theunprotected and/or protected modified elastomeric polymers may bepresent. For example, steam stripping of the polymer solution containingthe modified polymer according to Formula 5 will remove a percentage ofthe protecting trialkyl silyl groups resulting in the unprotected formwith the thiol (—SH) group exposed. Alternatively, a water-free work upprocedure can enable the preparation of the modified polymers accordingto Formula 5.

While not wishing to be bound by theory, it is believed that theunprotected thiol (—SH) group of the modified elastomeric polymer isreactive with both unsaturated portions of the polymer backbone, andfillers (such as silica and/or carbon black) present. This interactionis believed to result in the formation of bonds, or in the case of somefillers, electrostatic interactions which result in more homogeneousdistribution of filler within an elastomeric polymer compositions.

The resulting modified elastomeric polymer preferably comprises sulfidegroups (e.g. thiol) in the amount from 0.0010 to 0.20 or 0.0020 to 0.20mmol/gram of elastomeric polymer, preferably from 0.0010 to 0.10mmol/gram, and more preferably from 0.0025 to 0.1 mmol/gram, and evenmore preferably from 0.0025 to 0.05 or 0.0030 to 0.05 mmol/gram ofpolymer. In another embodiment, the sulfide groups are present in anamount less than, or equal to, 0.20 mmol/gram of elastomeric polymer,preferably less than, or equal to, 0.10 mmol/gram, and more preferablyless than, or equal to, 0.05 mmol/gram. In another embodiment, thesulfide groups are present in an amount greater than, or equal to,0.0010 mmol/gram of elastomeric polymer, preferably greater than, orequal to, 0.0020 mmol/gram, and more preferably greater than, or equalto, 0.0030 mmol/gram.

For most applications, the modified polymer is preferably a homopolymerderived from a conjugated diolefin, a copolymer derived from aconjugated diolefin monomer with an aromatic vinyl monomer, and/or aterpolymer of one or two types of conjugated diolefins with one or twotypes of aromatic vinyl compounds. More preferably, the modified polymeris a copolymer of a conjugated diolefin monomer with an aromatic vinylmonomer, e.g. a copolymer of butadiene with styrene with a sulfide group(e.g. thiol) bonded to at least some polymer chain ends.

Preferred chain end modified polymers (or modified elastomeric polymers)include, but are not limited to, chain end modified polybutadiene, chainend modified polyisoprene, chain end modified butadiene-styrenecopolymers, chain end modified butadiene-isoprene copolymers, chain endmodified isoprene-styrene copolymers and chain end modifiedbutadiene-isoprene-styrene terpolymers. Of the aforementioned polymers(or elastomeric polymers) chain end modified polybutadiene and chain endmodified butadiene-styrene copolymers are especially preferred.

Although there are no specific limitations regarding the content of1,2-bond and/or 3,4-bonds (hereinafter called “vinyl bonds”) of theconjugation diolefin portion of the elastomeric polymer, for mostapplications the vinyl bond content is preferably from 10 to 90 weightpercent, and particularly preferably from 15 to 80 weight percent. Ifthe vinyl bond content in an elastomeric polymer is less than 10 weightpercent, the resulting product may have inferior wet skid resistance. Ifthe vinyl content in the elastomeric polymer exceeds 90 weight percentvinyl bonds, the product may exhibit compromised tensile strength andabrasion resistance, and relatively large hysteresis loss.

Although there are no specific limitation regarding the amount ofaromatic vinyl monomer used in the subject modified elastomeric polymer,in most applications the aromatic vinyl monomers comprise from 5 to 60weight percent of the total monomer content, and more preferably from 10to 50 weight percent. Values less than 5 weight percent can lead toreduced wet skid properties, abrasion resistance, and tensile strength;whereas values more than 60 weight percent lead to increased hysteresisloss. The modified elastomeric polymer may be a block or randomcopolymer, but preferably 40 weight percent or more of the aromaticvinyl compound units are linked singly, and 10 weight percent or lessare of “blocks” in which eight or more aromatic vinyl compounds arelinked successively. The length of successively linked aromatic vinylunits can be measured by an ozonolysis-gel permeation chromatographymethod developed by Tanaka, et al. (Polymer, Vol. 22, Pages 1721-1723(1981)).

While dependant upon the specific polymer and desired end useapplication, the inventive modified polymers, as final bulk polymerreaction product, prior to rubber compounding and vulcanizationprocesses, preferably have Mooney viscosity values (ML 1+4, 100° C., asmeasured in accordance with ASTM D 1646 (2004)) in the range from 20 to150, and preferably from 30 to 100, using a Monsanto MV2000 instrument.Modified polymers may optionally include filler and/or oil and/or otherpolymers. If the Mooney viscosity (ML 1+4, 100° C.) is less than 20,abrasion resistance and hysteresis loss properties are compromised.Moreover, tack and cold flow of the elastomeric polymer are increased,resulting in difficult handling, poor green strength and poor storagestability. If the Mooney viscosity (ML 1+4, 100° C.) of the polymer ismore than 150, processability (filler incorporation and heat build up inthe internal mixer, banding on the roll mill, extrusion rate, extrudatedimensional stability. smoothness, etc.) is impaired and the cost ofprocessing increases.

In one embodiment of the invention, the modified polymer, as final bulkpolymer reaction product, prior to rubber compounding and vulcanizationprocesses, contains an oil, and has a Mooney Viscosity (ML 1+4, 100° C.,as measured in accordance with ASTM D 1646 (2004), as discussed above)in the range from 20 to 150, and preferably from 30 to 100. In anotherembodiment, the modified polymer, as final bulk polymer reactionproduct, prior to rubber compounding and vulcanization processes, doesnot contain filler or oil, and has a Mooney Viscosity (ML 1+4, 100° C.,as measured in accordance with ASTM D 1646 (2004), as discussed above)in the range from 20 to 150, and preferably from 30 to 100.

The preferred molecular weight distribution of the subject modifiedpolymer, as final bulk polymer reaction product, prior to rubbercompounding and vulcanization processes, and prior to the addition ofoil, filler or a second elastomeric polymer source, represented by theratio of the weight average molecular weight to the number averagemolecular weight, (Mw/Mn), ranges preferably from 1.3 to 3.0.Processability of the polymer is impaired if the Mw/Mn is less than 1.3.Poor processability not only increases cost of production, but alsoimpairs blending characteristics of components, such as insufficientdispersion of fillers and other additives, which may result in poorphysical properties. If Mw/Mn is more than 3.0, the content of lowmolecular weight components increases and hysteresis loss increases.

The inventive modified polymers (or modified elastomeric polymers) maycontain a combination of two or more features or embodiments asdescribed herein. To the aforementioned, especially preferred modifiedpolymers are as follows:

-   -   1) modified polybutadiene in a Mooney range of 30 to 80 and a        vinyl bond content ranging from 5 to 30 weight percent, based on        the conjugation diolefin portion of the modified elastomeric        polymer as discussed above,    -   2) modified polybutadiene in a Mooney range of 30 to 80 and a        vinyl bond content ranging from 45 to 80 weight percent, based        on the conjugation diolefin portion of the modified elastomeric        polymer as discussed above,    -   3) modified butadiene-styrene copolymer in a Mooney range from        45 to 80, a vinyl bond content ranging from 50 to 80 weight        percent, based on the conjugation diolefin portion of the        modified elastomeric polymer as defined above, and a styrene        content of 15 to 30 weight percent (in the copolymer), having 50        weight percent or more of the styrene units linked singly, and        10 weight percent or less linked to “blocks” of eight or more        styrene units, and    -   4) modified butadiene-styrene copolymer in a Mooney range from        45 to 80, a vinyl bond content ranging from 5 to 50 weight        percent, based on the conjugation diolefin portion of the        modified elastomeric polymer as discussed above, and a styrene        content of 30 to 55 weight percent (in the copolymer), having 40        weight percent or more of the styrene units linked singly, and        10 weight percent or less linked to “blocks” of eight or more        styrene units.

Mooney viscosity is measured as discussed above.

Extension oils may be used in combination with the subject elastomericpolymers to reduced viscosity or Mooney values. The invention providesfor compositions comprising a chain end modified elastomeric polymer andan oil. Applicable extender oils include mineral oils which are mixturesof aromatic-type oil, alicyclic-type oil, and aliphatic-type oil, andare classified as an aromatic-type extender oil, alicyclic-type extenderoil, or aliphatic-type extender oil. Among these, aromatic-type mineraloil having a viscosity gravity constant (V.G.G. value) of 0.900-1.049(aromatic oil) and an alicyclic-type mineral oil having a V.G.G. valueof 0.850-0.899 (naphthenic oil) are particularly preferable to ensureoptimal low temperature hysteresis loss properties resulting inexcellent wet skid resistance. Such extension of modified polymer of thesubject invention with extender oil ensures homogeneous dispersion offillers such as carbon black and silica in the polymer, and improvesprocessability and various properties of vulcanized products. The amountof extender oil used in the present invention is from 0 to 100 parts byweight, preferably from 0 to 80 parts by weight, and more preferablyfrom 0 to 70 parts by weight, for 100 parts by weight modifiedelastomeric polymer, as final bulk polymer reaction product, prior torubber compounding and vulcanization processes. When the extender oil isadded to the polymer solution, the timing of addition should be aftermodification of the polymer or termination of the polymerization, forexample, after the addition of the modifier or polymerizationtermination agent. After the addition of extender oil, the oil-extendedpolymer is obtained by separating the polymer from solvent by a directdrying method or steam stripping, drying the rubber using a vacuumdryer, hot-air dryer, roller, or the like. By way of example, US2005/0159513 published on Jul. 31, 2005 discloses an oil extended rubbercomposition comprising a solution-polymerized elastomeric polymercoupled with a silicon or tin coupling agent, and a low polycyclicaromatic oil.

In an important embodiment of the present invention, the subjectmodified polymer is combined and reacted with filler(s) andvulcanization agent, and optionally additional constituents, including,but not limited to, accelerators, coupling agents, and unmodifiedelastomeric polymers (i.e. conventional elastomeric polymers that havenot been reacted with the subject modifier but that have been preparedand terminated as is conventional in the art). The term “elastomericpolymer composition” is intended to describe the reaction productresulting from this combination. The resulting elastomeric polymercomposition it typically molded into a desired configuration andvulcanized to elastomeric article, such as a tire.

The subject modified elastomeric polymer or polymers (include oilextended embodiments) preferably comprises at least 30 weight percent ofthe total elastomeric polymer present, and more preferably at least 50weight percent. The remaining portion of the elastomeric polymer isunmodified elastomeric polymer. Preferred unmodified elastomericpolymers include: cis-1,4-isoprene polymer, natural rubber, 3,4-isoprenepolymer, styrene/butadiene copolymer polymer, styrene/isoprene/butadieneterpolymer, cis-1,4-butadiene polymer, trans-1,4-butadiene polymer, lowto high vinyl butadiene polymers (having a vinyl content of 10-90percent), acrylonitrile/butadiene copolymers, and chloroprene polymers.Of these, styrene-butadiene copolymer, natural rubbers, polyisoprene,and polybutadiene are preferable. It is desirable that the unmodifiedpolymers have a Mooney viscosity (ML 1+4, 100° C.) in the range from 20to 200, and preferably from 25 to 150 (measured in accordance with ASTMD 1646 (2004) as discussed above). The addition of unmodified polymersin the above range ensures manufacturing of the elastomeric compositionof the present invention at a low cost without substantially impairingits characteristics.

The subject elastomeric composition preferably includes fillers whichserve as reinforcement agents. Carbon black, silica, carbon-silicadual-phase-filler, clay, calcium carbonate, magnesium carbonate, and thelike are examples. Of these, the combined use of carbon black andsilica, the use of carbon-silica dual-phase-fillers alone, or thecombined use of carbon-silica dual-phase-filler and carbon black and/orsilica are preferable. Carbon black is manufactured by a furnace methodand having a nitrogen adsorption specific surface area of 50-200 m²/gand DBP oil absorption of 80-200 ml/100 grams, for example, FEF; HAF,ISAF, or SAF class carbon black, is preferable. High agglomeration typecarbon black is particularly preferable. Carbon black is typically addedin an amount from 2 to 100 parts by weight, and preferably from 5 to 100parts by weight, more preferably 10 to 100 parts by weight and even morepreferably 10 to 95 parts by weight, for 100 parts by weight of thetotal elastomeric polymer.

Examples of silica fillers include: wet process silica, dry processsilica, and synthetic silicate-type silica. Silica with a small particlediameter exhibits a high reinforcing effect. Small diameter, highagglomeration-type silica (i.e. that having a large surface area andhigh oil absorptivity) exhibits excellent dispersability in theelastomeric polymer composition, representing desirable properties, andsuperior processability. An average particle diameter of silica, interms of a primary particle diameter, is preferably from 5 to 60 μm, andmore preferably from 10 to 35 μm. Moreover, the specific surface area ofthe silica particles (measured by the BET method) is preferably from 45to 280 m²/g. Silica is added in an amount from 10 to 100 parts byweight, preferably 30 to 100 parts by weight, and even more preferablyfrom 30 to 95 parts by weight, for 100 parts by weight of the totalelastomeric polymer.

Carbon black and silica may be added together; in which case the totalamount of carbon black and silica added is from 30 to 100 parts byweight, and preferably from 30 to 95 parts by weight for 100 parts byweight of the total elastomeric polymer. So long as such fillers arehomogeneously dispersed in the elastomeric composition, increasingquantities (within the above cited ranges) result in compositions havingexcellent rolling and extruding processability, and vulcanized productsexhibiting favorable hysteresis loss properties, rolling resistance,improved wet skid resistance, abrasion resistance, and tensile strength.

Carbon-silica dual-phase-filler may be used either independently or incombination with carbon black and/or silica in the present invention.Carbon-silica dual-phase-filler can exhibit the same effects as thoseobtained by the combined use of carbon black and silica, even in thecase where this is added alone. Carbon-silica dual-phase-filler is socalled silica-coating-carbon black made by coating silica over thesurface of carbon black, and is commercially available under thetrademark CRX2000, CRX2002, or CRX2006 (products of Cabot Co.).Carbon-silica dual-phase-filler is added in the same amounts aspreviously described with respect to silica. Carbon-silicadual-phase-filler can be used in combinations with other fillers, e.g.carbon black, silica, clay, calcium carbonate, and magnesium carbonate.Of these fillers, use of carbon black and silica, either individually orin combination, is preferable.

It is preferable to add a silane coupling agent to the polymercomposition when silica or carbon-silica dual-phase-filler is used. Thetypical amount of a silane coupling agent added is from about 1 to about20 parts by weight, and preferably from 5 to 15 parts by weight, for 100parts by weight of the total amount of silica and/or carbon-silicadual-phase-filler. A silane coupling agent, which has both a functionalgroup reactive with silica surface such as for example but not limitedto an alkoxysilyl group and a functional group reactive with acarbon-carbon double bond of polymer such as polysulfide group, mercaptogroup, or epoxy group in the molecule is preferable including:bis-(3-triethoxysilylpropyl)tetrasulfide,bis-(3-triethoxysilylpropyl)disulfide,bis-(2-triethoxysilylethyl)tetrasulfide,bis-(2-triethoxysilylethyl)disulfide, 3-mercaptopropyltrimethoxysilane,3-triethoxysilyipropyl-N,N-dimethylthiocarbamoyltetrasulfide,3-triethoxysilylpropylbenzothiazole tetrasulfide,3-octanoylthio-1-propyltriethoxysilane (NXT silane, © CromptonCorporation). Additional examples are described in U.S. 2006/0041063A,incorporated herein by reference. The use of such a silane couplingagent increases the reinforcing effect brought about by the combined useof carbon black and/or silica or the use of carbon-silicadual-phase-filler.

In one embodiment of the invention, the modified polymer (or modifiedelastomeric polymer) contains a vulcanizing agent and/or a vulcanizingaccelerator. Sulfur-containing compounds and peroxides are the mostcommon vulcanizing agents. A vulcanizing accelerator of sulfeneamide-type, guanidine-type, or thiuram-type can be used together with avulcanizing agent, as required. Other additives such as zinc white,vulcanization auxiliaries, aging preventives, processing adjuvants, andthe like may be optionally added. A vulcanizing agent is typically addedto the polymer composition in an amount from 0.5 to 10 parts by weight,and preferably from 1 to 6 parts by weight, for 100 parts by weight ofthe total elastomeric polymer. Additional information regardingvulcanizing agents can be found in Kirk-Othmer, Encyclopedia of Chemicaltechnology 3^(rd), Ed, Wiley Interscience, N.Y. 1982, volume 20, pp.365-468, specifically “Vulcanizing Agents and Auxiliary Materials” pp.390-402.

In one embodiment an inventive vulcanized elastomeric polymercomposition comprises from 10 to 100 parts by weight filler, and from0.5 to 10 parts by weight of vulcanization agent, both based upon 100parts by weight of total elastomeric polymer in the composition.

In another embodiment, the invention provides a tire tread comprising,or formed from, an inventive vulcanized elastomeric polymer composition.In yet another embodiment, the invention provides a tire comprising atleast one component formed from an inventive vulcanized elastomericpolymer composition.

The elastomeric polymer composition of the present invention can beprepared by kneading the above-described modified elastomeric polymers(including oil extended varieties), unmodified elastomeric polymers(including oil extended varieties), fillers (carbon black, silica,carbon-silica dual-phase-filler, etc.), silane coupling agents, andother additives in a kneader at 140 to 180° C. After cooling,vulcanizing agents such as sulfur, vulcanizing accelerators, and thelike are added, and the resulting mixture is blended using a Banburymixer or open roll mill, formed into a desired shape, and vulcanized at140 to 180° C., thereby obtaining a vulcanized elastomeric product.

Because the vulcanized elastomeric polymer compositions of the presentinvention exhibit low rolling resistance, low dynamic heat build up andsuperior wet skid performance, the elastomeric polymer compositions ofthe present invention are well suitably for use in preparing tires, tiretreads, side walls, and carcasses, as well as other industrial productssuch as belts, hoses, vibration-proof rubber, and footwear.

The present invention will be explained in more detail by way ofexamples, which are not intended to be limiting of the presentinvention.

EXAMPLES

The following Examples are provided in order to further illustrate theinvention and are not to be construed as limiting. The Examples includethe preparation of the subject modifiers along with comparativemodifiers, the preparation and testing of modified elastomeric polymersand the preparation and testing of elastomeric polymer compositions.Unless stated to the contrary, all parts and percentages are expressedon a weight basis. The term “overnight” refers to a time ofapproximately 16-18 hours and “room temperature” refers to a temperatureof about 20-25° C. The polymerizations were performed under exclusion ofmoisture and oxygen in a nitrogen atmosphere. Various methods were usedto test and measure Examples. A brief description of these techniques isprovided.

The ratio between the 1,4-cis-, 1,4-trans- and 1,2-polydiene content ofthe butadiene or isoprene polymers was determined by IR, ¹H-NMR- and¹³C-NMR-spectroscopy (NMR (Avance 400 device (¹H=400 MHz; ¹³C=100 MHz)of Bruker Analytic GmbH). The vinyl content in the conjugated diolefinpart was additionally determined by IR absorption spectrum (Morellomethod, IFS 66 FT-IR spectrometer of Bruker Analytic GmbH). The IRsamples were prepared using CS₂ as swelling agent.

Bonded styrene content: A calibration curve was prepared by IRabsorption spectrum (IR (IFS 66 FT-IR spectrometer of Bruker AnalytikGmbH). The IR samples were prepared using CS₂ as swelling agent.). Thestyrene content was alternatively determined by NMR technique (NMR(Avance 400 device (¹H=400 MHz; ¹³C=100 MHz) of Bruker Analytik GmbH)).

A single chain aromatic vinyl compound unit (a unit with an aromaticvinyl compound linked singly) and a long chain aromatic vinyl compoundunit (a unit in which eight or more aromatic vinyl compounds are linked)was determined by NMR technique (NMR (Avance 400 device (¹H=400 MHz;¹³C=100 MHz) of Bruker Analytik GmbH)). Particularly, the total styreneblock content was determined through ¹H-NMR analysis of the signals inthe area from 6.2 to 6.9 ppm, reflecting all styrene blocks with morethan three styrene units (n≧3). The styrene micro blocks with n=3-5correspond to the signals in the area from 6.7 to 6.9 ppm and the longblocks with n>6 and n=6 correspond to the signals from 6.2 to 6.7 ppm.

Molecular weight distribution (Mw/Mn) was determined from the ratio ofpolystyrene-reduced weight average molecular weight (Mw) and numberaverage molecular weight (Mn), which were measured by gel permeationchromatograph (SEC with viscosity detection (universal calibration) inTHF at room temperature). Mp1 and Mp2 correspond to the molecular weightmeasured at the first and second maximum peaks of the GPC curve,respectively, of the uncoupled molecular weight fraction.

The glass transition (T_(g)) temperatures were determined by DSCdetermination. DSC (differential scanning calorimetry) was measuredusing a DSC 2920 of TA Instruments.

Mooney viscosity was measured according to ASTM D 1646 (2004) with apreheating time of 1 minute and a rotor operation time of 4 minutes at atemperature of 100° C. [ML1+4(100° C.)].

Modification efficiency with sulfanylsilanes was determined via (—SiMe₃)group and (—Si—OMe) group concentration by NMR technique (NMR (Avance400 device (¹H=400 MHz; ¹³C=100 MHz) of Bruker Analytic GmbH). (—Si—OMe)signal at 3.3-3.5 ppm and (—SiMe₃) signal at 0.1-0.2 ppm. To determinethe modification efficiency with an alkoxy group containingsulfanylsilane compound in percent, the value was divided by the numberaverage molecular weight (Mn) measured by GPC, as the measured value isthe amount of the Si—C bond per unit weight.

Modification efficiency with sulfanylsilanes was also determined viasulfur content as sulfate. The procedure required combustion of thesample in an automatic oven (Combustor 02 of the company GAMAB, Germany,Bad Dürrenberg) followed by absorption of the flue gas in water with0.1% hydrazinium hydroxide and subsequent determination of the sulfateconcentration with ion chromatography (Metrohm, column: Dionex IonPacAS12A).

Tensile strength, elongation at break and modulus at 300% elongation(Modulus 300) were measured according to ASTM D 412 on a Zwick Z010.

Heat build up was measured according to ASTM D 623, method A, on a Doli‘Goodrich’-Flexometer.

Tan δ (60° C.) was measured using the dynamic spectrometer Eplexor 150Nmanufactured by Gabo Qualimeter Testanlagen GmbH (Germany) applying acompression dynamic strain of 0.2% at a frequency of 2 Hz at 60° C. Thesmaller the index, the lower is the rolling resistance (lower=better).Tan δ (0° C.) was measured using the same equipment and load conditionsat 0° C. The larger the index, the better the wet skid resistance(higher=better).

DIN abrasion was measured according to DIN 53516. The larger the index,the lower the wear resistance is (lower=better).

Measurement of un-vulcanized rheological properties according to ASTM D5289 using a rotor-less shear rheometer (MDR 2000 E) to measure ScorchTime (TS) and Time to Cure (TC). The “TC 50” and “TC 90” are therespective times required to achieve 50 percent and 90 percentconversion of the vulcanization reaction. “TS 1” and “TS 2” are: therespective times required to increase the torque by 1 dNm and 2 dNmabove the respective torque minimum (ML) during vulcanization.

In general, the higher the value for Elongation at Break, TensileStrength, Modulus 300, and Tan δ at 0° C., the better; whereas the lowerthe Tan 6 at 60° C., Heat Build up, and Abrasion, the better. PreferablyTS 1 is >1.5 minute, TS 2 is >2.5 minute, TC 50 is from 3 to 8 minutes,and TC 90 is from 8 to 19 minutes.

Modifier Preparation: Four modifiers were used in the Examples. Thestructural formula and method of preparation (or source for obtaining)are provided below. Modifiers 1 and 2 are representative of those of thepresent invention, whereas modifiers 3 and 4 are for comparativepurposes.

Modifier 1 is represented by Formula M1 below, and was prepared asfollows:

A 250 mL Schlenk flask was charged with 100 g cyclohexane, 8.6 g (85mmol) triethylamine and 13.12 g (80 mmol) gamma-mercaptopropyltrimethoxy silane [Silquest A-189] from the Cromton GmbH. 17.9 g (165mmol) trimethyl chloro silane were diluted with 50 g cyclohexane and theresulting solution is then added drop wise to the Schlenk flask.Immediately a white triethylammonium chloride precipitated. Thesuspension was stirred for about 24 hours at room temperature, and foranother three hours at 60° C. The white precipitate was subsequentlyseparated by filtration. The resulting colorless solution was distilledin the vacuum to yield 16 g (67.7 mmol) of modifier 1.

Modifier 2 is represented by Formula M2 below and was prepared asfollows:

A 250 mL Schlenk flask was charged with 100 g cyclohexane, 8.6 g (85mmol) triethylamine and 14.4 g (79.8 mmol) gamma-mercaptopropyl(methyl)dimethoxysilane from the ABCR GmbH. 17.4 g (160 mmol) trimethyl chlorosilane were diluted with 50 g cyclohexane, and the resulting solution isthen added drop wise to the Schlenk flask. Immediately a whitetriethylammonium chloride precipitated. The suspension was stirred forabout 24 hours at room temperature and for another three hours at 60° C.The white precipitate was subsequently separated by filtration. Theresulting colorless solution was distilled in the vacuum to yield 17.2 g(68.1 mmol) of modifier 2.

Modifier 3 is represented by Formula M2 below and was prepared asfollows:

A 250 mL Schlenk flask was charged with 100 g cyclohexane, 8.6 g (85mmol) triethylamine and 8.85 g (80.0 mmol) gamma-mercaptopropyl chloridefrom the Aldrich GmbH. 17.4 g (160 mmol) trimethyl chloro silane werediluted with 50 g cyclohexane and the resulting solution is then addeddrop wise to the Schlenk flask. Immediately a white triethylammoniumchloride precipitated. The suspension was stirred for about 24 hours atroom temperature and for another three hours at 60° C. The whiteprecipitate was subsequently separated by filtration. The resultingcolorless solution was distilled in the vacuum to yield 11.9 g (65.3mmol) of modifier 3.

Modifier 4 is represented by Formula M4 below and was prepared asfollows:

Gamma-mercaptepropyl trimethoxy silane 4 [Silquest A-189] from theCromton GmbH.

Modifier 1 represented by Formula M1 above alternatively was prepared asfollows:

100 mL Schlenk flask was charged with 25 ml tetrahydrofuran (THF), 79.5mg (10 mmol) lithium hybrid and subsequently with 1.80 g (10 mmol)gamma-mercaptopropyl trimethoxy silane [Silquest A-189] from the CromtonGmbH. The reaction mixture was stirred for 24 hours at room temperatureand another two hours at 50° C. Than 1.09 g (10 mmol) trimethyl chlorosilane were diluted with 10 g THF and the resulting solution is thenadded drop wise to the Schlenk flask. Lithium chloride precipitated. Thesuspension was stirred for about 24 hours at room temperature, and foranother two hours at 50° C. The THF solvent was removed in the vacuum(vacuum?). Than 30 ml cyclohexane are added. The white precipitate wassubsequently separated by filtration. The cyclohexane solvent wasremoved in the vacuum (under reduced pressure). The resulting colorlessliquid solution proved to be 99 percent pure per GC and therefore nofurther purification was necessary.

2.2 g (9.2 mmol) of modifier 1 were obtained.Modifier 1 Represented by Formula M1 Above Alternatively was Prepared asfollows:

100 mL Schlenk flask was charged with 1.80 g (10 mmol)gamma-mercaptopropyl trimethoxy silane [Silquest A-189] from the CromtonGmbH, 25 ml tetrahydrofuran (THF) and subsequently with 0.594 g (11mmol) sodium methanolate (NaOMe) dissolved in 10 mL THF. The reactionmixture was stirred for 18 hours at room temperature. Than 1.09 g (10mmol) trimethyl chloro silane were diluted with 10 g THF, and theresulting solution is then added drop wise to the Schlenk flask. Sodiumchloride precipitated. The suspension was stirred for about 24 hours atroom temperature, and for another two hours at 50° C. The THF solventwas removed in the vacuum. Than 30 ml cyclohexane are added. The whiteprecipitate was subsequently separated by filtration. The cyclohexanesolvent was removed in the vacuum (under reduced pressure). Theresulting colorless liquid solution proved to be 89% pure per GC.Further purification consisted in a fractionated distillation.

1.7 g (7.2 mmol) of modifier 1.

Homopolymerization of 1,3-Butadiene Examples 1/1a and 2/2a

Polymerizations for Examples 1/1a and 2/2a were performed in a doublewall two liter steel reactor which was purged with nitrogen before theaddition of organic solvent, monomers, polar coordinator compound,initiator compound or other components. The polymerization reactor wastempered to 50° C., unless stated otherwise. The following componentswere than added in the following order: cyclohexane solvent (500 grams);tetramethylethylene diamine (TMEDA) (45.0 mmol) as polar coordinatorcompound, butadiene monomer, and the mixture was allowed to stir for onehour. N-butyl lithium (50.0 mmol) was added to start the polymerizationreaction. The polymerization was performed at 50° C. for approximately 2hours, after which time, a part of the polymer solution was removed fromthe reactor, and separately worked up as described below. Subsequently,the modifier (1 or 2) was added. For Examples 1a and 2a, no modifier wasadded. For the termination of the polymerization process, the polymersolution was transferred after one hour into a separate double wallsteel reactor containing 50 mL methanol, and Irganox 1520 as stabilizerfor the polymer (1 Liter of methanol contained two grams of Irganox).This mixture was stirred for 15 minutes. The polymerization solvent andother volatiles were then removed via vacuum.

Examples 1 & 1a

The polymerization reaction was performed using 54.1 g (1.00 mol)butadiene. After the removal of 66.6% of the polymer solution, 5.91grams (25.0 mmol) of modifier 1 was added to the polymerization reactor.The same preparation was used for Example 1a, except that no modifier asadded.

Examples 2 & 2a

The polymerization reaction was performed using 10.0 g (0.185 mol)butadiene. After the removal of 50% of the polymer solution, 12.5 mmolof modifier 2 was added to the polymerization reactor. The samepreparation was used for Example 2a, except that no modifier as added.

TABLE 1 —S —SiMe₃ Vinyl content —OMe content Mw Mn Mp1 Mp2 Tg contentmmol/g content mmol/g Ex Modifier g/mol g/mol g/mol g/mol ° C. mol %polybutadiene mol % polybutadiene 1 1 4,560 3,460 2,230 4,550 −51.8 63.10.20 0.0 0.17 1a none 2,350 2,080 2,230 NP* −58.0 66.1 0.0 0.0 0.0 2 2930 575 520  1500 49.5 0.83 0.1 0.89 2a none 520 430 540 NP* 51.5 0.00.0 0.0 *NP = Not present.

The GC-MS investigation of Example 2 confirmed the existence oftrimethyl silyl groups (—SiMe₃) (m/e=73) exemplary in three differentpolymer fractions, at retention times of 13.17 minutes, 13.25 minutesand 22.04. The (—SiMe₃) fragment was found in the majority of thepolymer fractions indicating the existence of at least one (—SiMe₃)group in the majority of the polymer chains.

As a separate study, effective removal of the (—SiMe₃) protective groupwas demonstrated by first preparing hexadecyl-trimethylsilyl-sulfide,followed by the removal of (—SiMe₃) group with HCl. More specifically,5.1 g (20 mmol) hexadecylthiol was dissolved in 25 mL cyclohexane.Triethylamine, 2.15 g (21.25 mmol) was then added followed by 4.47 g(41.25 mmol) chloro-trimethyl-silane in 25 mL cyclohexane. The resultingreaction mixture was stirred for 24 hours, and than heated at 60° C. forthree hours. The resulting solution was filtrated, and the cyclohexanesolvent removed via vacuum. Hexadecyl-trimethylsilyl-sulfide was formed,(yield: 6.6 g (20.0 mmol)). The (—SiMe₃) group was confirmed via NMRspectroscopy (signal appeared in the ¹H-NMR spectra at 0.23 ppm).Hexadecyl-trimethylsilyl-sulfide, 1 gram (mmol), was dissolved in 15 mLcyclohexane, and 2 grams hydrochloric acid (36%) in 10 mL ethanol wereadded and stirred for 15 hours at room temperature. After removal of theorganic layer through phase separation and extraction, the organic phasewas dried using magnesium sulfate and filtrated. Removal of the organicsolvent, and most of the formed hexachlorodisiloxane side product, viavacuum led to the isolation of hexadecylthiol. As expected, the (—SiMe₃)signal in the ¹H-NMR spectra at 0.23 ppm disappeared and a new (—SiMe₃)signal of very low intensity at 0.13 ppm appeared indicating thepresence of a hexachlorodisiloxane side product.

Copolymerization of 1,3-Butadiene with Styrene Examples 3-18

The co-polymerizations were performed in a double wall 20 liter steelreactor, which was first purged with nitrogen before the addition oforganic solvent, monomers, polar coordinator compound, initiatorcompound or other components. The polymerization reactor was tempered to40° C. unless stated otherwise. The following components were than addedin the following order: cyclohexane solvent (9000 grams); butadienemonomer, styrene monomer, tetramethylethylene diamine (TMEDA), and themixture was stirred for one hour followed by titration with n-butyllithium to remove traces of moisture or other impurities. Additionaln-butyl lithium was added as to start the polymerization reaction. Thepolymerization was performed for 80 minutes, not allowing thepolymerization temperature to exceed 60° C. Afterwards, 0.5% of thetotal butadiene monomer amount was added followed by the addition of tintetrachloride unless stated otherwise. The mixture was stirred for 20minutes. Subsequently, 1.8% of the total butadiene monomer amount wasadded, followed by the addition of modifier (1, 2, 3 or 4) unless statedotherwise. For the termination of the polymerization process, thepolymer solution was transferred after 45 minutes into a separate doublewall steel reactor containing 100 mL ethanol and 1.4 g of concentratedHCl (concentration 36%) and 5 g Irganox 1520 as stabilizer for thepolymer. This mixture was stirred for 15 minutes. The resulting polymersolution was than stripped with steam for one hour to remove solvent andother volatiles, and dried in an oven at 70° C. for 30 minutes andanother one to three days at room temperature.

The resulting polymer composition and several attributes are summarizedin Tables 2 and 3 below. Unless otherwise stated, quantities areexpressed in mmols. Examples prepared under identical polymerizationconditions (in the same polymerization reactor on the same day by thesame operator) are designated with identical letters adjacent to theExample number (e.g. 3A, 4A).

The use of a dash “-” in the tables below indicates that no constituentwas added. The abbreviation “N.M.” is intended to mean that nomeasurement was taken or that corresponding data was unavailable.

TABLE 2 Composition of Examples Tin butadiene styrene Example Modifiertetrachloride (moles) (moles) TMEDA n-butyl lithium  3A (1) — 29.18 4.0320.3 11.58 14.54  4A — 0.912 29.07 4.03 20.3 11.57  5B (1) 0.903 28.653.98 20.5 11.92 10.16  6B — 0.905 28.68 4.00 20.4 12.00  7C (2) 0.90528.66 3.99 20.3 10.22 10.16  8C — 0.909 28.59 4.01 20.3 10.13  9D (1) —28.94 4.00 20.3 13.39 14.54 10D (2) — 28.94 4.00 20.3 12.90 14.54 11D —0.905 28.68 4.00 20.3 12.55 12 (2) 0.911 28.99 4.01 20.6 12.33 10.16 13E(1) — 29.16 4.03 20.8 12.61 14.54 14E (3) 0.916 28.94 4.00 20.7 12.41 14.154 15E — 0.916 28.94 4.00 20.7 12.31 16 (4) 0.910 28.97 4.01 20.711.63 10.16 17 (4) — 29.27 4.01 20.8 12.98 10.16 18 — 0.912 28.96 4.0120.7 11.54

TABLE 3 Polymer Attributes Mooney Vinyl Styrene Example Modifier Mw MnMp1 Tg [° C.] viscosity content content  3A 1 377,580 298,201 262,163−26.1 63.2 62.6 20.8  4A — 421,181 291,149 267,668 −27.8 50.1 62.8 20.6 5B 1 496,873 342,581 250,450 −24.6 72.6 62.4 21.0  6B — 385,665 274,553249,431 −24.7 42.7 63.1 21.1  7C 2 494,999 323,521 292,319 −24.1 71.062.4 21.2  8C — 495,724 309,278 294,782 −29.0 69.8 21.0 20.1  9D 1318,595 241,301 224,954 −24.2 44.7 61.3 20.9 10D 2 292,750 246,318233,442 −24.6 34.9 63.3 20.4 11D — 363,924 254,332 238,329 −24.0 41.261.0 21.1 12 2 423,860 297,208 244,784 −24.0 56.6 62.8 21.0 13E 1341,280 275,095 240,784 −24.5 50.8 63.2 21.0 14E 3 395,383 259,723242,742 −23.6 48.9 62.9 22.5 15E — 387,818 254,950 244,784 N.M 41.0 62.922.5 16 4 479,761 336,551 259,462 −23.8 70.4 63.4 22.2 17 4 307,998256,067 234,889 −23.8 33.7 63.3 21.3 18 — 378,798 261,361 261,361 N.M41.9 62.8 20.9 *NM = Not Measured

The total styrene block content percentage for Examples 12-18 was ≦1%,with total long block content (greater than or equal to 5 repeat styreneunits) ≦5%, with the remainder being micro block content (from 2-4repeating styrene units).

Polymer compositions were prepared by combining and compounding theconstituents listed below Table 4, in a 350 cc Banbury mixer, andvulcanized at 160° C. for 20 minutes. Vulcanization process data andphysical properties for the each elastomeric composition example areprovided in Tables 5 and 6.

TABLE 4 Polymer Composition Amount Constituent (phr) Elastomeric polymerExample (styrene 100 butadiene copolymer) IRB 7 (international ref.carbon black, 50 Sid Richardson) Stearic acid 1.5 Zinc oxide 3.0 Softner(aromatic oil) 5.0 Vulcanization Package: Sulfur 1.75 CBS(N-cyclohexyl-2-benzothiazylsulfenamid; 1.0 Vulcacit CZ/EG, Bayer AG)

TABLE 5 Vulcanization Process Data DIN abrasion TS 1 TS 2 TC 50 TC 90Heat build 0.5 kg load Example Modifier [min] [min] [min] [min] up [°C.] [mm]  3A 1 3.75 5.49 7.31 14.33 88.7 162  4A — 4.41 6.33 8.50 15.8799.7 161  5B 1 4.86 5.94 7.77 14.90 89.6 152  6B — 4.68 6.54 8.78 16.32101.3 164  7C 2 4.20 5.73 7.72 15.26 87.0 151  8C — 4.32 6.48 8.71 15.994.1 157  9D 1 4.35 5.49 7.24 14.26 91.7 141 10D 2 4.35 5.34 7.02 14.1489.7 130 11D — 4.68 6.54 8.80 16.48 100.5 157

TABLE 6 Polymer Composition Properties Coupling Tensile Temp. at AgentElongation Strength Modulus Tan δ Tan δ at Tan δ Ex. Modifier (SnCl₄) atbreak [%] [MPa] 300 [MPa] at 0° C. 60° C. max [° C.]  3A 1 — 393 19.913.8 0.5312 0.0987 −12.05  4A — Yes 413 18.4 12.4 0.4745 0.1176 −11.95 5B 1 Yes 435 22.2 13.5 0.5965 0.0895 −10.05  6B — Yes 427 18.6 12.30.4703 0.1380 −11.95  7C 2 Yes 394 19.9 13.6 0.575 0.0933 −12.05  8C —Yes 384 17.7 12.7 0.5311 0.1130 −12.05  9D 1 — 418 21.1 13.6 0.58290.0961 −11.85 10D 2 — 424 20.3 13.1 0.5795 0.10591 −11.65 11D — Yes 44719.5 11.7 0.5386 0.1191 −10.85

Additional polymer compositions were prepared by combining andcompounding the constituents listed below Table 7 in a 350 cc Banburymixer and vulcanized at 160° C. for 20 minutes. Vulcanization processdata and physical properties for the each elastomeric compositionexample are provided in Tables 8 and 9.

TABLE 7 Polymer Composition Amount Constituent (phr) Elastomeric polymerExample (styrene butadiene copolymer) 80 High cis 1,4-polybutadiene(Buna cis 132-BSL GmbH) 20 Precipitated silica (Ultrasil 7000 GR,Degussa-Huls AG) 80 Silane (NXT silane, Degussa AG) 9.7 Stearic acid 1.0Antiozonant (Dusantox 6 PPD (N-(1,3-dimethyl-butyl)-N′- 2.0phenyl-p-phenyllendiamin) Duslo) Zinc oxide 2.5 Ozone protecting wax(Anitlux 654, Rhein Chemie Rheinau 1.5 GmbH) Softener (aromatic oil) 20Vulcanization Package: Sulfur 1.4 CBS(N-cyclohexyl-2-benzothiazylsulfenamid; Vulcacit 1.5 CZ/EG, Bayer AG)DPG (diphenylguanidin, Vulkacit D, Lanxess Deutschland 1.5 GmbH)

TABLE 8 Vulcanization Process Data DIN Abrasion TS 1 TS 2 TC 50 TC 90Heat build 0.5 kg load Example Modifier [min] [min] [min] [min] up [°C.] [mm]  3A 1 3.13 4.40 6.15 13.66 91.7 101  4A — 3.32 3.98 5.70 15.10115.6 108  5B 1 3.67 4.52 6.15 14.09 98.2 122  6B — 3.36 3.99 5.66 15.20122.6 135  7C 2 3.34 4.26 5.99 14.08 101.6 98  8C — 3.20 3.90 5.49 13.89112.6 96  9D 1 3.57 4.61 6.24 13.77 97.5 116  10D 2 3.24 4.15 5.74 13.3497.1 109  11D — 3.42 4.05 5.77 15.81 123.6 111  12 2 2.91 3.77 5.5314.38 N.M. 114  13E 1 3.6 4.5 6.1 13.2 N.M. 108  14E 3 3.7 4.4 6.3 15.3N.M. 109  15E — 3.8 4.5 6.4 16.0 N.M. 108  16 4 3.12 3.82 5.54 14.62N.M. 104  17 4 3.08 3.84 5.64 15.14 N.M. 132  18F — 3.15 3.78 5.46 15.38N.M. 115 *19F 1 3.03 3.65 5.36 15.20 N.M. 114 *0.24 g (0.894 mmol) ofModifier 1 were added to 120 grams the polymer composition of Example 18during compounding (i.e. after polymerization).

TABLE 9 Polymer Composition Properties Coupling Elongation TensileModulus Temp. at Agent at break Strength 300 Tan δ at Tan δ at Tan δ Ex.Modifier (SnCl₄) [%] [MPa] [MPa] 0° C. 60° C. max [° C.]  3A 1 — 49222.8 10.2 0.2309 0.0845 −21.95  4A — Yes 561 19.0 7.8 0.2800 0.1413−21.95  5B 1 Yes 472 20.8 10.2 0.2428 0.0951 −21.95  6B — Yes 590 19.07.7 0.2677 0.1609 −15.15  7C 2 Yes 503 21.8 9.8 0.2535 0.0968 −21.95  8C— Yes 543 20.0 8.1 0.2739 0.1329 −21.95  9D 1 — 463 21.2 10.5 0.23630.0898 −21.95  10D 2 — 471 21.4 10.7 0.2268 0.0888 −22.05  11D — Yes 60018.6 6.9 0.2608 0.1600 −23.75  12 2 Yes 499 20.8 9.25 0.2552 0.1009−21.95  13E 1 — 470 19.9 9.4 0.2282 0.0876 −22.08  14E 3 Yes 573 19.07.8 0.2739 0.1614 −21.85  15E — Yes 591 18.1 6.8 0.2756 0.1709 −21.95 16 4 Yes 514 18.7 8.2 0.2708 0.1269 −22.05  17 4 — 540 18.4 7.9 0.27310.1342 −21.75  18F — Yes 576 18.7 7.1 0.2698 0.1632 −21.85 *19F 1 Yes592 18.6 7.1 0.2652 0.1598 −24.05 *0.24 g (0.894 mmol) of Modifier 1were added to 120 grams the polymer composition of Example 18 duringcompounding (i.e. after polymerization).

One important application of the present invention is the production ofelastomeric polymer compositions having lower Tan δ at 60° C. valueswithout negatively impacting other physical properties andprocessability, particularly Tan δ at 0° C. Tire treads made fromelastomeric polymer compositions having lower Tan δ at 60° C. valueshave corresponding lower rolling resistance, while those with higher Tan6 at 0° C. values have corresponding better wet skid properties.

As means of illustrating the invention, living low molecular weightpolybutadienes were used as a relatively simple model polymer. As shownin Table 1, polybutadienes of Examples 1a and 2a had molecular weights(Mw) of 2,350 and 520 g/mol respectively. These polymers did not containmodified polymer chains, i.e. neither trimethylsilyl (—SiMe₃) normethoxy (—OMe) groups where present. Similar polymers (Examples 1 and 2)were prepared and modified with Modifiers 1 and 2 pursuant to thesubject invention. This modification resulted in a doubling of theaverage molecular weight (Mw), confirming the modification of polymerchains via the methoxy-silyl groups of the modifiers. As expected, fewmethoxy groups were detected in the ¹H-NMR spectra. Both theinvestigation of Example 2 by GC-MS analysis and the investigation ofExample 1 by pyrolysis-MS analysis lead to the identification of atrimethylsilyl (—SiMe₃) group as a fragment in the mass spectra atm/e=73.2. The molar concentration of sulfur and trimethylsilyl groups ineach of the Examples is in the same range, i.e. about 26 percent ofModifier 1 was attached to the polymer chain ends in Example 1, whileabout 34 percent of the Modifier 2 was attached to the polymer chainends of Example 2.

In order to demonstrate the potential effective removal oftrimethylsilyl group from a trimethylsilylsulfido-group modifiedpolymer, hexadecyl-trimethylsilyl-sulfide was selected as a modelcompound. As demonstrated above, hexadecyl-trimethylsilyl-sulfide wastransformed quantitatively into hexadecylthiol after the exposure tohydrochloric acid at room temperature. It is believed that the existenceof the trimethylsilyl group temporarily prevents (i.e. protects) theinactivation of a substantial amount of living polymer chain endsthrough reaction.

As previously stated, one significant application for the subjectmodified elastomeric polymers is their use in preparing elastomericpolymer compositions, and specifically tire treads, made therefrom,having low rolling resistance as represented by compositions havingrelatively low values for tan δ at 60° C., without significantlydeterioration of wet skid properties as represented by tan δ at 0° C. Asillustrated in Table 6, polymer compositions prepared from elastomericpolymers modified according to the present invention (i.e. with Modifier1 or 2) had relatively lower δ at 60° C. and higher tan δ at 0° C.values, as compared to their counterpart Examples (designated by thesame letter, e.g. 5A and 6A), prepared without such modification.Additionally, the Tensile Strength, Modulus 300, and Elongation at Breakof the modified Examples were generally improved, or at least notsignificantly deteriorated.

As shown by Examples 18F and 19F, it is important that the subjectliving elastomeric polymers are modified with the subject modifiers,rather than simply adding the modifier to the elastomeric compositionduring the compounding step after the elastomeric polymers have beenprepared and terminated. More specifically, as shown by the data inTable 9, the addition of Modifier 1, in comparable concentration as usedfor chain end modification, to the elastomeric composition after polymertermination, (as described in U.S. Pat. No. 6,229,036) had little impacton the values of tan 6 at 60° C. or 0° C.

As shown in Table 6, Heat build up during vulcanization is reduced byuse of the subject modified elastomeric polymers. This reduction isbelieved to improve the durability of the resulting composition, and toincrease overall elasticity. Similarly, Tensile Strength and Modulus 300are improved, suggesting the formation of a stable polymer network witha higher resistance under mechanical stress. Although Elongation atBreak values are slightly reduced, they are still very acceptableconsidering the improved Tensile Strengths and Tan δ values.

Tables 5 and 8 show that scorch times (TS) and times to cure (TC) arecomparable with unmodified polymers and have good processability.

It is particularly advantageous that aforementioned benefits weregenerally found with both carbon black containing polymer compositionsas well as with silica containing polymer compositions.

1. A chain end modified elastomeric polymer, comprising the reactionproduct of: i) a living anionic elastomeric polymer, and ii) asilane-sulfide modifier represented by the formula:(RO)_(x)(R)_(y)Si—R′—S—SiR₃ wherein: Si is silicon; S is sulfur; O isoxygen; x is an integer selected from 1, 2 and 3; y is an integerselected from 0, 1, and 2; x+y=3; R is the same or different and is(C₁-C₁₆) alkyl; and R′ is aryl, and alkyl aryl, or (C₁-C₁₆) alkyl. 2.The chain end modified elastomeric polymer of claim 1, wherein R′ is a(C₁-C₁₆) alkyl.
 3. The chain end modified elastomeric polymer of claim1, wherein each R group is the same or different, and each isindependently a (C₁-C₅) alkyl, and wherein R′ is (C₁-C₅) alkyl.
 4. Thechain end modified elastomeric polymer of claim 1, wherein the reactionproduct further comprises at least one coupling agent, selected from thegroup consisting of tin halide, tin alkoxide, silicon halide, andsilicon alkoxide.
 5. The chain end modified elastomeric polymer of claim1, wherein the modified elastomeric polymer is selected from the groupconsisting of modified homopolymers of isoprene, modified homopolymersof butadiene, modified copolymers of butadiene with styrene, modifiedcopolymers of isoprene with styrene, modified terpolymers butadiene withisoprene and styrene, and combinations thereof.
 6. A vulcanizedelastomeric polymer composition comprising the reaction product of thefollowing: 1) a filler; 2) a vulcanization agent; and 3) a chain endmodified elastomeric polymer, and wherein the chain end modifiedelastomeric polymer is the reaction product of: i) a living anionicelastomeric polymer, and ii) a silane-sulfide modifier represented bythe formula:(RO)_(x)(R)_(y)Si—R′—S—SiR₃ wherein: Si is silicon; S is sulfur; O isoxygen; x is an integer selected from 1, 2 and 3; y is an integerselected from 0, 1, and 2; x+y=3; R is the same or different and is:(C₁-C₁₆) alkyl; and R′ is aryl, alkylaryl, or (C₁-C₁₆) alkyl.
 7. Thecomposition of claim 6, wherein R′ is a (C₁-C₁₆) alkyl.
 8. Thecomposition of claim 6, further comprising an oil.
 9. The composition ofclaim 6, wherein each R group is the same or different, and each is a(C₁-C₅) alkyl, and wherein R′ is (C₁-C₅) alkyl.
 10. The composition ofclaim 6, wherein the reaction product further comprises at least onecoupling agent, selected from the group consisting of tin halide, tinalkoxide, silicon halide, and silicon alkoxide.
 11. The composition ofclaim 6, wherein the filler comprises silica.
 12. The composition ofclaim 6, wherein the filler comprises carbon black.
 13. The compositionof claim 6 wherein the chain end modified elastomeric polymer isselected from the group consisting of modified homopolymers of isoprene,modified homopolymers of butadiene, modified copolymers of butadienewith styrene, modified copolymers of isoprene with styrene, modifiedterpolymers butadiene with isoprene and styrene, and combinationsthereof.
 14. The composition of claim 6, comprising from 10 to 100 partsby weight filler, and from 0.5 to 10 parts by weight of vulcanizationagent, both based upon 100 parts by weight of total elastomeric polymer.15. A tire tread comprising the vulcanized elastomeric polymercomposition of claim
 6. 16. A method for making a vulcanized elastomericpolymer composition, said method comprising combining at least thefollowing constituents: 1) a filler; 2) a vulcanization agent; and 3) achain end modified elastomeric polymer which is the reaction product of:i) a living anionic elastomeric polymer, and ii) a silane-sulfidemodifier represented by the formula:(RO)_(x)(R)_(y)Si—R′—S—SiR₃ wherein: Si is silicon; S is sulfur; O isoxygen; x is an integer selected from 1, 2 and 3; y is an integerselected from 0, 1, and 2; x+y=3; R is the same or different and is:(C₁-C₁₆) alkyl; and R′ is aryl, alkylaryl, or (C₁-C₁₆) alkyl.
 17. Themethod of claim 16, wherein R′ is a (C₁-C₁₆) alkyl.
 18. The method ofclaim 16, wherein the composition further comprises an oil.
 19. Acomposition comprising the following: (a) the chain end modifiedelastomeric polymer of claim 1, and (b) an oil.
 20. The chain endmodified elastomeric polymer of claim 1, wherein the modifiedelastomeric polymer is selected from the group consisting of modifiedhomopolymers of butadiene and modified copolymers of butadiene withstyrene.
 21. The composition of claim 6 wherein the chain end modifiedelastomeric polymer is selected from the group consisting of modifiedhomopolymers of butadiene and modified copolymers of butadiene withstyrene.
 22. The chain end modified elastomeric polymer of claim 1,wherein the living anionic elastomeric polymer is selected from thegroup consisting of homopolymers of isoprene, homopolymers of butadiene,copolymers of butadiene with styrene, copolymers of isoprene withstyrene, terpolymers butadiene with isoprene and styrene, andcombinations thereof.
 23. The composition of claim 6, wherein the livinganionic elastomeric polymer is selected from the group consisting ofhomopolymers of isoprene, homopolymers of butadiene, copolymers ofbutadiene with styrene, copolymers of isoprene with styrene, terpolymersbutadiene with isoprene and styrene, and combinations thereof.